Aircraft floor incorporating a ground plane

ABSTRACT

A system for shielding of at least one component within an aircraft includes a floor panel disposed at least partially between joists supporting a floor within the aircraft and a ground plane connected to a bottom surface of the floor panel. The ground plane extends at least partially between adjacent joists. At least one bracket electrically connects the ground plane to at least one of the joists.

CROSS REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY

This application is a Divisional of U.S. patent application Ser. No.14/772,429 filed on Feb. 26, 2014, which is a national phase applicationunder 35 U.S.C. 371 of International Patent Application No.PCT/IB2014/000209 filed on Feb. 26, 2014, which claims priority to U.S.provisional patent application No. 61/773,441 filed on Mar. 6, 2013, theentire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention concerns a construction incorporating a protectiveground plane into a floor panel of an aircraft, a bracket for connectingthe ground plane to a joist supporting a floor panel in an aircraft, anda system combining the ground plane and bracket for grounding the groundplane within an aircraft. The ground plane is contemplated to provideisolation from electromagnetic and radio frequency sources, among othertypes of electrical protection.

DESCRIPTION OF THE RELATED ART

In the construction of traditional aircraft, it has been the practice ofaircraft manufacturers to place wire bundles at strategic locationswithin the fuselage of the aircraft. The wire bundles include wires thatprovide power to various devices located on the aircraft. The wires alsocarry electrical signals between devices located on the aircraft and,therefore, provide electronic communication between those variousdevices.

As should be apparent to those skilled in the art, it is known toprovide electrical shielding for the wire bundles within the aircraft.Electrical protection (or shielding) encompasses insulating (orisolating) wires from interference from one or more sources ofelectromagnetic and/or radio frequency sources.

With respect to electromagnetic and radio frequency transmissions, itshould be apparent that there are various sources of potentiallyinterfering signals. Interference may be generated by components thatare part of the aircraft. Separately, passengers and crew members maybring devices on board the aircraft (i.e., cellular telephones, tablets,computers, etc.) that may generate electromagnetic (“EM”) and/or radiofrequency (“RF”) signals that have the potential to interfere withsignals transmitted along the wire bundles. A third potential source ofEM and RF signals are those generated exterior to the aircraft. Forexample, communications towers (i.e., cellular towers, radio towers,etc.) may generate signals that are of sufficient strength to interferewith aircraft systems, even from an appreciable distance.

A simple way to provide electrical protection for one or more wires isto position the wires near to a grounded, electrically conductivesubstrate. Typically, the substrate is made from metal, because metalmaterials are excellent conductors. In addition, metal materialsfunction well to protect electrical signals in wires from beinginfluenced by EM and RF interference.

As should be apparent to those skilled in the art, the skin oftraditional aircraft is made from aluminum or an alloy of aluminum.Being made from metal, the skin of the traditional aircraft offers aconvenient surface against which wire bundles may be positioned. As aresult, it has been common practice to lay wire bundles adjacent to (orin close proximity) to the interior surface of the skin of the aircraft.By positioning the wire bundles adjacent to the skin of the aircraft,the traditional aircraft designer has been able to provide EM and RFshielding for those wires.

More and more, modern aircraft incorporate non-metallic components. Forexample, modern aircraft incorporate carbon fiber composite materialsinto at least some of the panels forming the skin and other structuralcomponents.

Carbon fiber composite materials are not particularly conductive whencompared to metals. As a general rule, carbon fiber materials are aboutone thousand times (1000×) less conductive than metals. Carbon fibermaterials, therefore, are inadequate for shielding wires from EM and RFinterference.

As should be apparent, with the substitution of carbon fiber compositematerials for metal in modern aircraft, the skin of the aircraft may nolonger act as a suitable ground location, to establish an EM shieldand/or RF shield for the wire bundles positioned adjacent thereto.

Separately, given the space requirements in aircraft, it is contemplatedthat the wire bundles may not be placed adjacent to the skin of theaircraft, even where the aircraft is made entirely from metal.

As a result, a need has developed for a light-weight EM/RF shield forelectrical wire bundles disposed within the aircraft, regardless of thepositioning of the wire bundles in the aircraft. In other words, a needdeveloped a way to shield electrical wires regardless of their positionwithin the aircraft.

SUMMARY OF THE INVENTION

The present invention addresses one or more of the deficiencies notedwith respect to the prior art.

In one contemplated embodiment, the present invention provides a systemfor shielding of at least one component within an aircraft. The systemincludes a floor panel disposed at least partially between joistssupporting a floor within the aircraft, a ground plane connected to abottom surface of the floor panel, the ground plane extending at leastpartially between adjacent joists, and at least one bracket electricallyconnecting the ground plane to at least one of the joists.

In another embodiment of the system of the present invention, the groundplane shields the at least one component from at least one ofelectromagnetic and radio frequency interference.

It is contemplated that the ground plane is made of a plate ofelectrically conductive material and at least one hole provided in theplate to lighten the total weight of the plate. The hole is sized forshielding of the at least one component, accommodating at least one offrequency and wavelength of impingent radiation upon the at least onecomponent.

It is calculated that the hole is no more than about 1/10^(th) of thesize of a minimum wavelength of the impingent radiation.

The bracket that forms a part of the invention includes a body defininga first end and a second end. The first end connects to a ground planeand the second end connects to the joist. At least one first fastenerconnects the first end to the ground plane. At least one second fastenerconnects the second end to the joist. A spacer connects to the firstend, establishing a contact surface between the spacer and the groundplane. A seal surrounds the spacer.

Another embodiment of the present invention provides a ground plane forshielding of at least one component within an aircraft. The ground planeincludes a plate of electrically conductive material, and at least onehole provided in the plate to lighten the total weight of the plate. Thehole is sized for shielding of the at least one component, accommodatingat least one of frequency and wavelength of impingent radiation upon theat least one component. As noted, the hole may be no more than about1/10^(th) of the size of a wavelength of the impingent radiation. In oneembodiment, the hole is about 1.2 inches in diameter.

It is contemplated that the ground plane shields the at least onecomponent from at least one of electromagnetic and radio frequencyinterference.

The component may be a wire bundle disposed adjacent to the groundplane.

The ground plane is contemplated to be made from metal.

The present invention also provides a bracket for connecting a groundplane to a joist for shielding of at least one component within anaircraft. The bracket includes a body defining a first end and a secondend, wherein the first end connects to a ground plane and wherein thesecond end connects to the joist, at least one first fastener connectingthe first end to the ground plane, at least one second fastenerconnecting the second end to the joist, a spacer connected to the firstend, establishing a contact surface between the spacer and the groundplane, and a seal surrounding the spacer.

The spacer is contemplated to be made from an electrically conductivematerial.

The bracket is contemplated to be made from metal.

The spacer is contemplated to include a peripheral portion and an innerportion with a thickness greater than that of the peripheral portion.

The seal surrounding the spacer is contemplated to be made from anelastomeric material.

Further aspects of the present invention will be made apparent form theparagraphs that follow.

BRIEF DESCRIPTION OF THE DRAWING(S)

The present invention will now be described in connection with thedrawing appended hereto, in which:

FIG. 1 is a perspective illustration of an aircraft that incorporatesthe features of the present invention;

FIG. 2 is a graphical cross-section of an aircraft fuselage,illustrating a conventional location for the placement of wire bundleswithin the aircraft fuselage;

FIG. 3 is a graphical cross-section of the aircraft fuselage of thepresent invention, illustrating at least one challenge associated withthe placement of wire bundles within the interior of the aircraft;

FIG. 4 is a graphical cross-section of the aircraft fuselage of thepresent invention, showing at least one contemplated placement of groundplane(s) beneath the floor of the aircraft's cabin;

FIG. 5 is a perspective illustration of one embodiment of the groundplane and bracket(s) of the present invention;

FIG. 6 is an enlarged, cross-sectional view of embodiment of the groundplane and brackets illustrated in FIG. 5;

FIG. 7 is a perspective, top view of one of the brackets illustrated inFIG. 6, with the floor panel having been removed for clarity; and

FIG. 8 is a graphical top view, showing two implementations of theground panel and brackets of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT(S) OF THE INVENTION

The present invention will now be described in connection with one ormore embodiments thereof. The discussion of any particular embodiment isnot intended to be limiting of the present invention. To the contrary,the discussion of selected embodiments is intended to exemplify thebreadth and scope of the present invention. As should be apparent tothose skilled in the art, variations and equivalents of theembodiment(s) described herein may be employed without departing fromthe scope of the present invention. Those variations and equivalents areintended to be encompassed by the scope of the present patentapplication.

The present invention will now be discussed in the content of theconstruction of an aircraft 10, such as the one illustrated in theperspective view provided in FIG. 1.

FIG. 1 is a perspective illustration of an aircraft 10 to which thepresent invention applies. The aircraft 10 includes a fuselage 12defining a forward end 14 and a rear (or aft) end 16. Two wings 18, 20extend laterally from the fuselage 12. A tail section 22 is attached tothe rear end 16 of the aircraft. As should be apparent to those skilledin the art, the wings 18, 20 and the tail section 22 incorporatemultiple control surfaces that are responsible for flyingcharacteristics and flight operations of the aircraft 10. Two engines24, 26 are suspended from and connect to the wings 18, 20, asillustrated.

As discussed above, all aircraft 10 include wire bundles 28 that performat least two primary functions. Some of the wires in the wire bundlestransfer power to one or more of the operational components within theaircraft 10. Others of the wires transmit electrical signals that areprocessed by one or more of the devices on the aircraft 10. As a result,it is desirable to provide shielding so that the wires in the wirebundles 28 are insulated (or isolated) from EM and RF influences. Asshould be apparent to those skilled in the art, EM and RF influences(among other variables) may impact upon the performance and/or operationof the wires in the wire bundles 28 in addition to interfering with oneor more components on board the aircraft.

FIG. 2 is a graphical cross-section of a conventional aircraft 10. Afloor 30 of the cabin 32 is provided for reference. As illustrated, wirebundles 28 are positioned adjacent to the interior surface 34 of thefuselage 12. The wire bundles 28 extend along the length of the aircraft10 from a position near to the front end 14 to a position near to therear end 16. As noted above, in the conventional aircraft 10, the skin36 of the aircraft 10 is made from a metal, in particular aluminum or analuminum alloy. The metal skin 36, therefore, provides a convenientlocation for the placement of the wire bundles 28 thereagainst. The skin36 of the aircraft 10 provides shielding from EM and RF sources.

As also discussed above, modern aircraft are, more and more,incorporating carbon fiber composite panels in lieu of aluminum parts.Carbon fiber panels, while lighter and (in some configurations) strongerthan their aluminum counterparts, are not particularly conductive. As ageneral rule, carbon fiber composite components are about 1000 timesless conductive than metals. As a result, carbon fiber components do notadequately shield the wire bundles 28 from EM and/or RF sources.

FIG. 3 is a graphical cross-section of the aircraft illustrated inFIG. 1. This cross section is provided to assist with a discussion ofspecific aspects of the present invention.

As should be apparent to those skilled in the art, the floor 30 issupported by joists 38, which are spaced from one another and extendalong the longitudinal axis of the aircraft 10. Cross joists (not shownin this illustration) extend laterally between the sides of the fuselage12 and connect the joists 38 together to form a checkerboard latticeunder the floor 30 within the cabin 32 of the aircraft 10.

As should be apparent to those skilled in the art, the joists 38typically are made from metal, such as aluminum or an aluminum alloy.Being made from metal, the joists 38 provide at least a limited degreeof grounding and protection against EM and RF interference. However, thedistance 40 between the joists 38 exceeds the protective distance 42established by the joists 38. As such, any wire bundles 28 that arepositioned adjacent to the joists 38 will not benefit from protectionfrom EM and RF interference because some portion of the wire bundles 28will lie outside of the protective distance 42 established by the joists38.

FIG. 4 illustrates one aspect of the present invention. Specifically, toprovide protection from EM and RF interference (hereinafter referred toas “electrical protection”), the aircraft 10 of the present inventionincorporates ground planes 44 that are positioned beneath the floor 30,above and adjacent to respective ones of the wire bundles 28.

The ground planes 44 are contemplated to be made from a conductivematerial, such as metal. In the illustrated embodiment, the groundplanes are made from aluminum or an aluminum alloy. The ground planeshave a width 46 that is at least as wide as the adjacent wire bundle 28.The wire bundles 28 are positioned sufficiently close to the groundplanes 44 so that they benefit from the electrical protectionestablished by the ground planes 44.

In the contemplated embodiment, the ground planes 44 have a width 46that is greater than the widths of the wire bundles 28 disposed adjacentthereto. In an alternative embodiment, the ground planes 44 may havewidths that are equal to the widths of the wire bundles 28. In a thirdcontemplated embodiment, the ground planes 44 may have widths 46 thatare less than the widths of the bundles 28 positioned adjacent thereto.In this third embodiment, it is understood that the ground planes 44establish electrical protection that extends a distance from the edgesthereof, just as the joists 38 establish a protective distance 42therefrom. Relying on this aspect of the ground planes 44, it iscontemplated that the ground planes 44 need not be as wide as theadjacent wire bundles 28.

As also is illustrated in FIG. 4, the ground planes 44 are contemplatedto be interposed between the floor 30 (which is made from a matrix offloor panels 30 that are connected to the joists 38 and the cross joists(not shown in this view)) and the wire bundles 28. In an alternativeembodiment, it is contemplated that the ground planes 44 may bepositioned within the aircraft 10 such that the wire bundles 28 arepositioned between the ground planes 40 and the floor 30 withoutdeparting from the scope of the present invention.

It is noted that the floor panels 30 provide a convenient location forthe location of the ground plane 44 of the present invention. Inaddition, the floor panels 30 are removable from the joists andcross-joists 48, thereby providing access to any wire bundles 28positioned thereunder.

FIG. 5 is a perspective view showing one contemplated embodiment of thepresent invention. The perspective is taken from a vantage point beneaththe floor 30 of the aircraft 10 looking upwardly at the bottom surfaceof one or more of the floor panels 30. The joists 38 are visible in thisillustration, as is at least one of the cross joists 48. The groundplane 44 is visible beneath the floor 30.

As should be apparent to those skilled in the art, the weight ofcomponents in the aircraft 10 is always a concern for aircraftdesigners. Specifically, aircraft designers endeavor to lighten aircraftcomponents so that they present a minimal weight addition to theaircraft 10 while performing their intended function(s). This designconsideration applies to the ground plane 44, just as it does with otheraircraft components.

So that the ground plane 44 offers sufficient electrical protection butdoes not add unnecessarily to the overall weight of the aircraft 10, theground plane 44 is constructed to be thin and to include a plurality ofholes 50 cut therethrough. With respect to the thickness of the groundplane 44, one embodiment contemplates that the ground plane 44 will bequite thin. For example, the ground plane 44 may be only ten onethousandths of an inch (0.01 inch; 0.254 mm) thick. It is contemplatedthat the ground plane 44 may be made thicker or thinner withoutdeparting from the scope of the present invention.

Being so thin, the ground plane 44 is more like an aluminum foil, ratherthan a rigid plate of metal. Being so thin, the ground plane 44preferably is affixed to the bottom surface of the floor 30 so that theground plane 44 is not easily torn or damaged. It is contemplated thatthe ground plane 44 may be applied to the floor 30 as a coating duringmanufacture of the floor 30. Alternatively, the ground plane 44 may beaffixed to the bottom of the floor 30 via any suitable adhesive or othersuitable attachment means.

As noted above, the ground plane 44 includes a plurality of holes 50 cuttherethrough. The holes 50 have a diameter that does not exceed amaximum size required for electrical protection.

One embodiment of the present invention contemplates that the holes 50will have diameters of about 1.2 inches (3.05 cm). It is alsocontemplated that the distance between holes 50 will not be less than1.2 inches (3.05 cm). This specific distance was selected based oncalculations associated with the frequency and wavelength of the typesof electrical threats anticipated to be present in the aircraft 10(i.e., electronic devices) or in the environment through which theaircraft 10 travels (i.e., communications towers).

It is noted that the holes are sized to accommodate specific wavelength(and frequencies) of EM and RF interference. The holes 50 have adiameter that is approximately 1/10 of the length of the shortestwavelength of the types of interfering EM and/or RF radiation that isanticipated to impinge thereon. Finally, while circular holes areillustrated, the holes 50 may have any shape without departing from thescope of the present invention.

As should be apparent, the ground plane 44 of the present invention isnot considered to be limited to this particular construction. Holes 50with a larger or smaller diameter may be employed without departing fromthe scope of the present invention. Moreover, the distance between theholes may be larger or smaller than 1.2 inches (3.05 cm) withoutdeparting from the scope of the present invention.

In one contemplated embodiment, the ground plane 44 does not include anyholes 50. While this adds weight to the aircraft 10, a solid groundplane 44 offers maximum shielding protection to any wire bundles 28positioned adjacent thereto.

So that the ground plane 44 is electrically grounded within the aircraft10, the ground plane 44 is connected to the joists 38 (or,alternatively, the cross joists 48) via one or more brackets 52. Thebrackets 52 are connected to the ground plane 44 and the floor 30 at afirst end 54, via one or more fasteners 56. The brackets 52 areconnected to the joists 38 at a second end 58 via one or more fasteners60.

At the first end 54, the bracket 52 and the ground plane 44 establish ametal-to-metal contact to ensure a reliable electrical connectiontherebetween. Similarly, at the second end 58, the bracket 52 and thejoist 38 present a metal-to-metal contact to ensure a reliable,electrical contact therebetween. As such, the ground plane 44 issuitably grounded via the network of supports made up of the joists 38and the cross joists 48 (among other components in the aircraft 10).

In FIG. 5, floor fasteners 62 also are illustrated. The floor fasteners62 removably connect the floor panels 30 to the joists 38 and the crossjoists 48. As should be apparent to those skilled in the art, the floorpanels 30 are designed to be removable so that personnel may access thecomponents (including the wire bundles 28) that are located beneath thefloor 30. Such access may be needed, for example, to perform maintenanceor repairs on the aircraft 10.

So that the floor panels 30 may be disengaged from the brackets 52, thefasteners 56 also are removable. The second ends 58 of the brackets 52are not contemplated to be removed easily from the joists 38 (orcross-joists 48) unless there is a need to replace one or more of thebrackets 52. In other words, the brackets 52 in this embodiment arecontemplated to remain affixed to the joists 38 after removal of one ormore of the floor panels 30.

FIG. 6 is a cross-sectional view of a portion of the ground plane 44 ofthe present invention, the cross section being taken through one of thefasteners 56. The perspective is looking toward one of the joists 38from the fastener 56.

The fastener 56 extends through the floor panel 30 and the first end 54of the bracket 52. The fastener 56 is surrounded by a first seal 64 thatextends through the floor panel 30. The first seal 64 helps to protectthe electrical connection between the ground plane 44 and the bracket52.

The first end 54 of the bracket 52 includes a spacer 66 that isconnected to and extends upwardly from a top surface of the bracket 52.The spacer 66 includes a thin, peripheral portion 68 and a thicker,inner portion 70.

The peripheral portion 68 of the spacer 66 is penetrated by at least onefastener 72 that connects the spacer 66 to the first end 54 of thebracket 52. As should be apparent, the illustrated embodiment providesroom for two fasteners 72. While two fasteners 72 are illustrated, alarger or a fewer number may be used without departing from the scope ofthe present invention.

The spacer 66 is electrically connected to the first end 54 of thebracket via a metal-to-metal contact. As should be apparent, the spacer66 is made from metal, such as aluminum. However, the spacer 66 may bemade from any other suitable, conductive material without departing fromthe scope of the present invention. The inner portion 70 of the spacer66 establishes an electrical contact 74 between the bracket 52 and theground plane 44. A second seal 76, made from an elastomeric materialsuch as rubber, surrounds the spacer 66. In addition to the first seal64, the second seal 76 helps to protect the electrical contact betweenthe spacer 66 and the ground plane 44. Specifically, the second seal 76discourages moisture and debris from entering the space around thespacer 66 and, thereby, protects the electrical connection 74 betweenthe spacer 66 and the ground plane 44.

FIG. 7 is a perspective illustration of the bracket 52 illustrated inFIGS. 5 and 6. The perspective is taken from above the bracket 52 withthe floor panel 30 having been removed.

FIG. 8 is a graphical top view of two contemplated installations of theground plane 44 according to the present invention.

On the right hand side of FIG. 8, the ground plane 44 extends nearly thefull distance between adjacent joists 38. On the left hand side, theground plane 44 extends partially between two adjacent joists 38.

It is noted that the embodiment provided on the left hand side of FIG. 8includes extensions 78 that extend outwardly from the ground plane 44 tothe edge of the floor plate 30 on which the ground plate 44 is disposed.The brackets 52 connect to the extensions 78 in the same manner as thebrackets 52 connect to the ground plane 44. Specifically, the brackets52 connect to the extensions 78 via one or more fasteners 56.

In another contemplated embodiment, it is contemplated that theextensions 78 may be substituted by elongated brackets (not shown) thatextend from the joists 38 (and/or cross-joists 48) to the ground plate44. The elongated brackets (no shown) are, therefore, considered to fallwithin the scope of the present invention.

In both embodiments, it is contemplated that four brackets 52 willconnect between the joists 38 and the ground planes 44 at roughly thecorners of the ground planes 44. This arrangement is preferred becausethe arrangement provides acceptable redundancy. Moreover, by connectingthe brackets at the corners of the ground planes 44, a betterdistribution of electrical protection is established. As should beapparent, however, a larger or a smaller number of brackets 52 may beemployed without departing from the scope of the present invention.

As should be apparent from the foregoing, the present invention iscontemplated to be disposed in an aircraft 10. The aircraft 10 may bemade entirely with a metal skin, with a partially metal skin withnonmetal portions, or entirely from a non-metallic material such ascarbon fiber composite.

As noted above, the embodiment(s) described herein are intended to beexemplary of the wide breadth of the present invention. Variations andequivalents of the described embodiment(s) are intended to beencompassed by the present invention, as if described herein.

What is claimed is:
 1. A bracket for connecting a ground plane to ajoist for shielding of at least one component within an aircraft,comprising: a body defining a first end and a second end, wherein thefirst end connects to a ground plane and wherein the second end connectsto the joist; at least one first fastener connecting the first end tothe ground plane; at least one second fastener connecting the second endto the joist; a spacer connected to the first end, establishing acontact surface between the spacer and the ground plane; and a sealsurrounding the spacer.
 2. The bracket of claim 1, wherein the spacercomprises: an electrically conductive material.
 3. The bracket of claim1, wherein the bracket comprises metal.
 4. The bracket of claim 1,wherein the spacer comprises: a peripheral portion; and an inner portionwith a thickness greater than that of the peripheral portion.
 5. Thebracket of claim 1, wherein the seal comprises an elastomeric material.6. The bracket of claim 1, wherein the ground plane shields the at leastone component from at least one of electromagnetic and radio frequencyinterference.